No. 495] SYMBIOSIS IN FEILX PROTHALLIA 



157 



and Ophioglossum. This suggested the possibility of its 

 occurrence in other green prothallia, and the forms which 

 seemed to promise best were the Marattiaeoa-, which in 

 many ways seem to be the nearest relatives of the ( )phio- 

 glossaceae, in whoso subterranean prothallia the endophyte 

 regularly occurs. I therefore made an effort to obtain 

 prothallia of the Marattiaceae while collecting in (Vylon 

 and Java, and procured prothallia of Am,wph 

 Hoffm, Kaulfnssio tvscxdifoUa Bl., and Marattia sawhn- 

 cina Bl. The two former were carefully studied, and as 

 was expected, the endophyte was found in nearly every 

 case. The prothallia of Marattia sambucma were not 

 examined, but the examination of a series of sections of 

 M. Douglasii Baker, made some years ago. showed that 

 in this species the endophyte was also present and pre- 

 sumably it occurs also in other species of Marattia. 



The other family of ferns in which it was thought the 

 endophyte might occur was the Gleicheniaceae, a small 

 family, mostly tropical and of wide distribution. The 

 Gleicheniaceae are considered to be related to the Os- 

 mundaceae and it was thought that they also might show 

 the presence of the endophyte. The prothallia have rarely 

 been collected, but are not difficult to find if one looks 

 for them carefully. Material of four species was secured, 

 one being collected near Cape Town, the others in Ceylon 

 and Java. In all cases the endophytic fungus was found 

 in the older prothallia. 



These investigations show conclusively that an endo- 

 phytic fungus is normally present in the green prothallia 

 of several Marattiacea*, Osmundaceae and Gleicheniaceae, 

 and it is highly probable that further research will show 

 similar fungal' endophytes occurring in the prothallia of 

 many other ferns. 



The Structure of the Endophyte 

 Since the discovery of the endophytic fungus in the 

 gametophyte of Botrychium, it has been found constantly 



